Single-ended electric incandescent lamp and mount assembly therefor



. J.J. PALERMo Erm. SINGLE-ENDED ELECTRIC INCANDESCENT LAMP Feb. 17,1970 AND MOUNT ASSEMBLY TnEnEFoR Filed March 28 INVENTORS James JPolermo 8 Arthur A. Bottone.

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United States Patent O 3,496,403 SINGLE-ENDED ELECTRIC INCANDESCENT LAMPAND MOUNT ASSEMBLY THEREFOR James J. Palermo, Methuen, Mass., and ArthurA.

Bottone, South Amboy, NJ., assignors to Westinghouse ElectricCorporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar.28, 1968, Ser. No. 716,822 Int. Cl. H01k 1/18; H013 1/88, 19/42 U.S. Cl.313-222 12 Claims ABSTRACT F THE DISCLOSURE A compact halogen-containingincandescent lamp having a multi-section coiled-coil filament that issuspended within the lamp envelope by a lcompressible wire support ringwhich is seated within a circumferential recess formed in the envelopewall. The support ring has a laterally extending hooked portion that iscoupled to a medial segment of the filament located between thecoiled-coil sections. The opposite ends of the coiled-coil sections ofthe filament are fastened to rigid lead-in conductors that extendthrough a press seal and are electrically connected to pin contactscarried by a base member attached to the press seal.

BACKGROUND OF THE INVENTION This invention relates to electricincandescent lamps and has particular reference to an improvedhalogen-containing projection lamp and a filament mount assembly forsuch a lamp.

Compact so-called halogen cycle incandescent lamps are well known in theart. Lamps of this type are more efficient and have a longer life thanconventional incandescent lamps in that the iodine or bromine atmospherethat is commonly used establishes a gettering cycle that returnsvaporized tungsten to the filament and markedly reduces the bulbblackening that would otherwise occur. Such halogen type lamps are thusadmirably suited for use in film projectors and the like where a compacthighly-efficient light source would permit the size of the projector tobe decreased without sacrificing picture brightness.

In order to concentrate as much of the light as possible at the filmgate of the projector, it is the common practice to use coiled-coilfilaments having a plurality of sections that extend longitudinally ofthe envelope and are disposed in side-by-side relationship. Prior artprojection lamps of this type have presented a problem in that a supportwire, or other suitable support means, which extends along and to oneside of the filament is required to hold the filament in the properupright position within the envelope. Mounts having suchlongitudinally-extending filament support structures are not onlydifficult and expensive to fabricate and assemble but reduce the usablelight output of the lamp since the support structure blocks light raysthat would otherwise pass directly out of the lamp into the opticalsystem of the projector, or light rays that would be redirected into theoptical system by the reflector located behind the lamp.

SUMMARY It is accordingly the general object of the present invention toprovide a compact incandescent lamp having a concentrated filament thatis supported in a predetermined position within the lamp envelope bymeans which can Abe conveniently and inexpensively fabricated and whichwill not impair the effective light output or efficiency of the lamp.

A more specific object is the provision of a single-ended halogen-cycleprojection lamp having a multi-section 3,496,403 Patented Feb. 17, 1970coiled-coil filament that is precisely oriented within the lamp and isheld in such position without obstructing light that would otherwiseenter the optical system of the projector.

Another object is the provision of a filament mount assembly for asingle-ended electric incandescent lamp that permits the filament to beconveniently and accurately suspended within the lamp envelope.

The foregoing objects and other advantages are achieved in accordancewith the present invention by supporting the upper end of the filamentby means of a compressible member that is seated within acircumferential recess provided in the inner wall of the bulb.Accordingly, to a preferred embodiment, a compressible loop of resilientwire is mechanically locked in an annular groove formed in the bulb Wallnear the domed top of the envelope. The loop has a radially extendingend portion that is terminated by a hook which supportingly engages themedial segment of a multi-section coiled-coil filament. The filamentlegs are attached to rigid lead-in wires anchored in a press Seal formedon the opposite end of the envelope so that the filament is suspended inpredetermined position within the envelope and the light rays can passthrough the side walls of the envelope without being obstructed.

BRIEF DESCRIPTION OF THE DRAWING A better understanding of the inventionwill be obtained by referring to the accompanying drawing, wherein:

FIGURES 1 and 2 are front and side sectional views, respectively, of a500` watt halogen-cycle projection lamp incorporating the presentinvention;

FIG. 3 is an exploded view of the lamp envelope and a filament mountassembly that is ready for insertion into the envelope; and

FIG. 4 is a front sectional view of an alternative lamp embodiment.

DESCRIPTION OF EMBODIMENT I In FIG. 1 there is shown one form of theinvention embodied in a 500 watt T6 incandescent projection lamp `10having a tubular vitreous envelope 12 of circular cross section that isterminated at one end by a rounded dome portion 14 having a protrudingsealed-off remnant 16 of a vitreous exhaust tube. The dome portion 14 isjoined to the cylindrical body portion 17 of the envelope 12 by aprotruding rim or bead 18 that defines an interiorcircumferentially-extending recess or groove 20 that is disposed in aplane which is substantially normal to the longitudinal axis of the lamp10. The opposite end of the envelope 12 is closed by a hermetic sealportion 22 which, in the embodiment here shown, constitutes a press sealof I-shaped cross section.

As will be noted in FIG. 2, the sides 19 of the envelope -body portion17 adjacent the press seal 22 taper inwardly toward and merge with theflat faces of the seal.

In accordance with this embodiment of the invention, a suitable filament23 of refractory material, such as a multi-section V-shaped coiled-coil(a so-called CCZV) fila-ment of tungsten wire, is centrally suspendedwithin the envelope 12 by means of a compressible support member such asa loop 28 of resilient wire that is seated in the circumferentialinterior groove 20 and 'is locked in such position solely by theenvelope Walls. The bead portion 18 of the envelope 12 is so formed, asshown in FIGS. l and 2, that the domed and body portions of the envelopeimmediately adjacent the wire loop 28 extend laterally for a shortdistance and form a pair of spaced annular shelves or seats that tightlylock the Iwire loop in position.

As will be noted more clearly in FIG. 3, the wire loop 28 in theparticular embodiment here shown comprises a closed circular ring thathas an overlapping arcuate end portion 29 and a radially-extendingstraight end portion 30 that is terminated by a retroverted bend whichconstitutes a hook 31. This hook engages the upwardly extending bight 26of the filament 23 that joins the two coiled-coil sections 24 and thusmaintains the filament in the desired suspended position. The hook 31 islocated at the center of the wire ring 28 and is thus aligned with thelongitudinal axis of the lamp The filament 23 is thus axially alignedwith respect to the envelope 12.

Returning to FIGS. l and 2, it will be noted that the lower end of thefilament 23 is held in place by attaching the straight leg sections 32of the respective coiledcoil sections 24 to rigid lead-in conductors 34that are anchored in the press seal 22. The conductors 34 are, in turn,fastened as by spot welding, to a pair of ribbon conductors 3-6. Theribbons are fastened to a pair of rigid outer lead wires 38 thatprotrude from the end of the press seal 22 and are electricallyconnected to a pair of pins 40 anchored in the bottom wall 41 of ahollow-base 42 attached to the press seal by a suitable high-temperaturecement 44. Exposed portions of both of the outer leads 38 are of reducedcross section and form fusible elements 46 that protect the lamp fromviolent failure when the filament 23 fails at the end of life. Only onesuch integral fuse can be used if desired. The bottom wall 41 of thebase 42 defines a fiat registration surface that is disposed in a planethat 'is normal to the longitudinal axis of the lamp 10 and is spaced apredetermined axial distance from the center of the filament 23. Theaforesaid registration surface thus determines the criticallight-center-length dimension of the lamp and insures that the filament23 will be accurately positioned relative to the optical axis of theprojector when the lamp 10 is seated in its socket.

In the case of a halogen-cycle lamp of the type here shown, the lampatmosphere preferably consists of bromine or iodinein which case theenvelope is made of quartz and the wire ring 28 and inner leads 34 arefabricated from tungsten or other suitable refractory material that willnot deleteriously react with the lamp atmosphere.

As will be noted in FIG. 3, the outer diameter of the ring support 28,when in relaxed condition, is slightly larger than the inner diameter ofthe cylindrical envelope 12. Thus, when the filament mount assembly 48(consisting of the ring support 28, coupled filament 23 and attachedlead-fin conductor assembly comprising the joined inner leads 34, ribbonconductors 36 and outer U-shaped lead member 38') is inserted into theenvelope 12 the ring will be constricted slightly and then expand intothe groove 20, thus locking the inner end of the mount in the envelope.The mouth of the envelope 12 is press sealed around the ribbons 36 andadjacent portions of the inner leads 34 and outer hairpin-like lead 38',and the latter is severed adajcent the U-bend to provide a pair ofexposed leads 38 (FIGS. l and 2) of the proper length. The envelope 12is then exhausted, filled with nitrogen (or argon, or a mixture of argonand nitrogen), dosed with a predetermined amount of a halogen (or ahalogen-forming compound) through the tube 16 and the latter is tippedoff.

The use of the hair-pin or U-shaped one-piece lead component 38' is animportant feature of the invention since it permits the mount 48 to bemade as a separate assembly and inserted into the envelope 12. The useof the ring support 28, iin addition to permitting the filament 23 to beaccurately suspended -within the envelope 12, also provides excellentelectrical insulation between the mount components since the support 28and inner leads 34 are located at opposite ends of the envelope.

EMBODIMENT II In FIG. 4 there is shown another lamp embodiment 10ahaving a different type of filament 50 and a modified wire ring support28a. The filament 50 comprises a socalled 2CC8 coil of tungsten wirehaving two coiledcoil sections 51, 52 that are disposed in parallelside-byside relation and joined by a laterally-extending medialcoiled-coil segment 53 consisting of approximately three secondaryturns. The radially extending end portion of the ring support 28a isterminated by a shallow U-shaped hook 31a that extends through andshorts out all of the secondary turns of the medial coiled-coil segment53. Thus, only the parallel-spaced coiled-coil sections 51, 52incandesce when the lamp is energized and serve as the light source.

In addition to serving as a point of anchorage for the filament 50, themedial coiled-coil segment 53 provides a resilient floating bridgestructure between the sections 51, 52 that permits them to expand andcontract freely as the lamp is turned off and on. Thus, distortion ofthe coil sections 51, 52 and variations in inter-coil spacing during thelife of the lamp are drastically reduced at no additional cost.

The lamp 10a is the same as lampy 10 as regards the configuration of theenvelope 12a, the manner in which the inner leads 34a are supportinglyjoined to the filament legs 54, 55, the construction of the base 44a,etc.

It will be appreciated from the foregoing that the objects of theinvention have been achieved in that an improved single-ended projectionlamp has been provided in which a multi-section filament of complexconfiguration is accurately and securely supported within the envelopewithout obstructing any usable light rays. An integral mount assemblythat can be conveniently and economically manufactured and sealed intothe lamp envelope has also been provided.

While several embodiments have been illustrated and described, it willbe understood that further modifications can be made without departingfrom the spirit and scope of the invention. For example, a 2CC8 filamentcan be used wherein the coiled-coil sections are joined by a singlycoiled section of bight instead of the short medial coiledcoil sectionof a few turns shown in Embodiment II. Of course, the filament can alsoconsist of a length of tungsten wire or other suitable refractorymaterial that is coiled but once.

We claim as our invention:

1. A single-ended electric incandescent lamp comprisa light-transmittingenvelope having a sealed portion at one end and a portion at itsopposite end that defines an interior circumferential recess,

a filament of refractory material suspended within said envelope, and

means supporting said filament in the aforesaid position comprising (1)a rigid lead-in conductor that is anchored in the sealed portion of saidenvelope and is fastened to one end of said filament and (2) acompressible member interlockingly seated in said circumferential recessand having a depending element that is coupled to a portion of saidfilament remote from the said one end thereof.

2. The electric lamp set forth in claim 1 wherein;

the sealed portion of said envelope comprises a press seal,

said lead-in conductor extends through said press seal,

a base member is fastened to said press seal, and

the outer end of said lead-in conductor is electrically connected to acontact carried by said base member.

3. The electric lamp set forth in claim 1 wherein;

said envelope is of tubular configuration,

said compressible member comprises a loop of resilient wire and saiddepending element comprises one end of said wire,

said filament is composed of refractory metal wire and includes twocoiled sections that are disposed in spaced side-by-side relationship,

the depending end of said wire defines a hook that supportingly engagesa medial segment of said filament that joins the coiled sectionsthereof,

said rigid lead-in conductor is fastened to the opposite end of one ofthe coiled sections of said filament, and

a second rigid lead-in conductor is anchored in the sealed portion ofsaid envelope and is fastened to the adjacent end of the other coiledsection of said filament.

4. The electric lamp set forth in claim 3 wherein said filament is ofcoiled-coil construction and generally V- shaped and the medial segmentthereof comprises a singlycoiled bight.

5. The electric lamp set forth in claim 3 wherein;

said filament is of coiled-coil construction and thetwo coiled sectionsare disposed in parallel-spaced relation,

the medial segment of said filament comprises a third coil sectionhaving several secondary turns, and

the hook portion of said wire support loop extends through and shortcircuits all of the secondary turns of said third coil section.

6. The electric lamp set forth in claim 3 wherein;

said filament, wire loop and lead-in conductors are composed oftungsten, and

said envelope contains a halogen atmosphere.

7. The electric lamp set forth in claim 6 wherein said envelope iscomposed of quartz and contains an iodine or bromine atmosphere.

8. The electric lamp set forth in claim 3 wherein;

the body portion of said envelope is of tubular configuration andcircular cross section, the recess-defining portion of said envelopemerges with a closed domed end portion,

said wire loop is of circular configuration and has an outer diameter,when in relaxed condition, that is slightly larger than the innerdiameter of the tubular body portion of said envelope, and

the depending end of said wire loop extends radially inward and isterminated by a retroverted bend that is substantially aligned with thelongitudinal axis of said envelope and forms said hook.

9. The electric lamp set forth in claim 8` wherein;

the sealed portion of said envelope comprises a press seal, and

the domed end portion of said envelope is terminated by a sealed-offremnant of a vitreous exhaust tubulation.

10. The electric lamp set forth in claim 9 wherein;

said filament is of coiled-coil construction,

a base is cemented to said press seal,

the protruding outer ends of said lead-in conductors are electricallyconnected to a pair of pin contacts that are anchored in the bottom wallof said base,

a portion of at least one of said lead-n conductors that is locatedwithin said base is of reduced diameter and constitutes a fuse element,and

the outer surface of the bottom wall of said base is spaced apredetermined distance from the center of said filament and constitutesa registration surface that controls the orientation of the filamentwith respect to the socket in which the lamp is used.

11. A mount assembly for an incandescent electric lamp comprising;

a filament of refractory metal wire having a pair of coiled sectionsthat are disposed in spaced side-byside relationship and are joined by amedial segment,

an arcuate loop of resilient wire that is disposed in a plane transverseto the filament axis and has a laterally extending portion whichincludes a hook that is coupled to the medial segment of said filament,and

a rigid U-shaped lead-in conductor member that eX- tends longitudinallyfrom and has its straight end sections fastened to the ends of therespective coiled sections of said filament.

12. The incandescent electric lamp mount assembly set forth in claim 11wherein;

said filament is of coiled-coil construction,

said wire loop is of closed circular configuration,

the laterally extending portion of said wire loop extends radiallyinward to the plane of the loop and is terminated by a retrovertedprotruding bend that constitutes said hook, and

the ends of the coiled sections of said filament that are fastened tosaid U-shaped lead-in conductor member are substantially straight.

References Cited UNITED STATES PATENTS 317,633 5/1885 Edison 313-2731,983,362 12/1934 Geiger et al 313-271 X 3,210,587 10/1965 Vile 313-271JAMES W. LAWRENCE, Primary Examiner P. C. DEMEO, Assistant Examiner U.S.Cl. X.R.

